Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756217AbaJ2SwF (ORCPT ); Wed, 29 Oct 2014 14:52:05 -0400 Received: from mail-lb0-f169.google.com ([209.85.217.169]:64944 "EHLO mail-lb0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755728AbaJ2SwD (ORCPT ); Wed, 29 Oct 2014 14:52:03 -0400 MIME-Version: 1.0 In-Reply-To: <20141029183612.GI6890@mwanda> References: <1414587599.5330.50.camel@dhcp-9-2-203-236.watson.ibm.com> <20141029183612.GI6890@mwanda> From: Andy Lutomirski Date: Wed, 29 Oct 2014 11:51:40 -0700 Message-ID: Subject: Re: [GIT PULL] Fix for Integrity subsystem null pointer deref To: Dan Carpenter Cc: Mimi Zohar , "linux-kernel@vger.kernel.org" , LSM List , Linus Torvalds , "security@kernel.org" , James Morris Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 29, 2014 at 11:36 AM, Dan Carpenter wrote: > On Wed, Oct 29, 2014 at 09:23:45AM -0700, Andy Lutomirski wrote: >> I have no idea what the semantics are. All I'm saying is that it >> looks like the code still accesses memory past the end of the buffer. >> The buffer isn't a null pointer, so the symptom is different, but it >> may still be a security bug. >> >> --Andy > > It only reads one byte into the struct "xattr_data->type" so checking > for non-zero is sufficient and the patch is fine. Indeed. Still... eww. I don't like code that, upon local inspection, is apparently wrong, even though it's coincidentally correct due to some other far away condition. --Andy > > I fixed that exact same bug in lustre last week where the xattr size is > not zero but it's less than the size of the struct. So this seems like > maybe it could be a common anti-pattern though. > > regards, > dan carpenter > -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/